1. Field of the Invention
This invention relates to a lumbar support system for securely supporting a person seated in the seat at his waist by making the upholstery sheet of the seat partially protrude at portions corresponding to air bags disposed behind the upholstery sheet of a vehicle seat by supplying air into an air bag, and more particularly, to a lumbar support system in which the degree of the protrusion of the upholstery sheet can optionally be adjusted.
2. Description of the Prior Art
Some vehicle seats, particularly some motor vehicle seats, are provided with a lumbar support at a position corresponding to the waist of the seated person. Usually, such a lumbar support is formed by providing a supporting pad behind the upholstery sheet of a vehicle seat so as to be movable with respect to the frame of the seat. The supporting pad is moved to a desirable position to adjust the relative position of the protrusion of the upholstery sheet corresponding to the position of the supporting pad with respect to the seated person.
When a mechanical means capable of selectively moving the supporting pad to a plurality of predetermined positions is employed as means to move the supporting pad, the supporting pad cannot be adjusted to an intermediate position between two predetermined positions. When a motor-driven means is employed as means to move the supporting pad, the supporting pad can be adjusted to an optional position, however, the motor-driven means requires complicated and costly mechanism.